The are 10 coloured balls in a bag, 4 red, 3 green, 2 orange and 1 yellow. John picks out balls and replaces them one at a time. What is the probability that the first two he picks are red?

The probability that John picks out a red ball is: The number of red balls divided by the total number of balls = 4/10
Because the balls are replaced, each event is independent so every time John picks out a ball the probability it is red is always 4/10. To determine the probability of two events both occurring we times their individual probabilities together.
Therefore the probability that the first two balls John picks out are red is: 4/10 X 4/10 = 16/100 which simplifies to 4/25